Electrode structure for gaseous discharge devices



Oct. 2, 1951 'r. F; JONES ELECTRODE STRUCTURE FOR'GASEOUS DISCHARGE DEVICES 2 Sheets-Sheet 1 Filed Oct. 25, 1945 Oct. 2, 1951 JONES 2,569,474

' ELECTRODE STRUCTURE FOR GASEOUS DISCHARGE DEVICES Filed 0st. 25, 1945 2 Sheets-Sheet 2 ISLE-3 THOMAS .F. JONES Patented Oct. 2, 1951 UNITED STATES PATENT OFFICE ELECTRODE STRUCTURE FOR GASEOUS DISCHARGE DEVICES Thomas F. Jones, Alexandria, Va.

Application October 25, 1945, SerialNo. 624,609

1 Claim. (Cl. 313-188) (Granted under the act March 3. 1883, as amended April .30, 1928; 370 O. G. 757) The present invention relates to electrical discharge devices and more particularly to an improved glow discharge device of the gas tube type- An object of the invention is the provision of an automatic bidirectional switching tube having a high impedance to voltages of the order of millivolts, and very low impedance to potentials of volts or greater.

Another object is to provide a bidirectional glow discharge valve capable of breaking down or firing at approximately 16 volts and capable of continuous operation on alternating current of given minimum frequency, with a voltage drop of less than five volts.

A further object is the provision of an ionic switching tube of both low, operating voltage drop and low internal capacity coupling between the electrodes.

A further object is the provision of an ionic discharge device with means for preventing ionic bombardment of portions whose reception of ions is not essential to effective operation of the device.

Various other objects and advantages of the invention will become apparent upon a perusal of the following specification and the drawings accompanying the same.

.In the drawings: Fig. 1 is an elevation about twice actual size,

with the envelope partly broken away and partly I in section.

ing a coating l2 of low work function material such as thorium oxide, and a heating element of any known or other suitable form, in the present instance a multiple heater element com- .prised of hair-pin heater elements l3 insulated I from the electrodes in any known or other suitable manner as by the usual ceramic covering H. The dimensions and spacing of the electrodes may be varied widely according to the use to which the tube is to be put. In the present embodiment the electrodes l0 and II are of about three thirty-seconds of an inch in diameter, about one and five-eighths inches long andspaced apart about three-quarters of an inch. These are enclosed in a sealed glass envelope l5 containing a suitable ionizable medium, in the present instance argon, preferably at a pressure of about 16 millimeters of mercury.

A glass press I 6 supports the various current leads, the heater current leads ll-l8 and |929 supporting a pair of heater-buses 2| and 22 respectively, which buses in turn support the electrodes through the ends of their respective heater elements I3. Connection of the ends of the heater elements is made by spot welding through an intermediate clip element 23. The current leads 24 and 25 for the electrodes connect Wlth\ the latter through electrode extensions 26 and 21.

Inasmuch as the device is of the gas discharge type, there will be a certain amount of ionic bombardment of the exposed lower ends of the heater elements 13, due to a difference in potential between the electrodes and the exposed heater ends caused by unavoidable coupling of the latter to ground through the distributed capacity of the various circuit connections. To prevent such bombardment, an auxiliary electrode 28 of lower work function than the exposed ends of the heater elements or other conductors to be protected, is provided. This auxiliary or protecting electrode is preferably of the'usual form of oxide coated, thermionic electrade, and it, too, has its heater terminals 29-30 connected to the heater buses Zl-ZZ by way of short bus-extensions 4'l48 (Fig. 2) which latter aid in supporting the electrode. An electrode extension 3| connects the electrode 28 with the current lead 32. By connecting the current lead 32 to one of the heater leads I! or iii, preferably outside the tube or envelope l5, any difierence in "potential, between the protective electrode 28 is directly electrically connected to all the heater elements at the same potential.

elements to maintain the electrode 28 and heater This results in that any of the electrodes and ground or other common return to the source supplying the electrodes, will cause ions to pass to the protection electrode in preference to the exposed ends of the heaters [3, to satisfy the current demand of the above mentioned capacity coupling which, of course, is usually kept as small as practical. Any known or other suitable form of connecting base, not shown, may be used. Also any known or other suitable form of electrode spacing and supporting means may be used in addition to the support afforded by the heater leads, for securely holding the electrodes in proper spaced relation. It is to be noted that the protecting electrode 28 is accessory and not essential to an effective operation of the device as an automatic, bidirectional, nonlinear discharge device.

It has been found that a device constructed as above described, will operate to offer a high impedance of between 10 and ohms to voltages of the order of millivolts with very low impedance at potentials of five volts or greater.

Tests show that a tube constructed substantially as above described while remaining in the nonconducting or high impedance state up to a given minimum applied voltage, say 16 volts, will remain in the conducting state with a potential difference of as low as 3 volts after application of the break-down voltage, substantially throughout the cycle of alternating currents at frequencies above 3 k. 0. thereby very effectively passing the usual range of to k. 0. without undue wave distortion.

Thus, with or without the use of the protective electrode, the device finds great usefulness highly sensitive receiving stations 3940 from tube noises or such other low intensityelectrical fnoises as may emanate from the output transformer 4|, and to prevent the relatively low voltage output from one of the transducers, when acting as energy pick-up devices, from reaching the receiving station of the other, back through the common connection of the transducers with the amplifier output transformer 4|. In the present example, the transducers are underwater, two-way electrosonic transducersyoperable either as underwater sound projectors or receiving microphones.

Where the protector electrodes 28 are used, their current leads 32 are connected outside their respective tubes to one of the heater leads, such I as the lead ill to provide current flow thereto or therefrom to satisfy the distributed capacity indicated at 42 and. existing between the various circuits and apparatus such as the heater transformers 53 and ground or other common return to the source of potential.

Modifications of the device embodying more than two working electrodes are useful where two or more circuits are to be controlled. Such modification is indicated diagrammatically at 43 in Fig. 4 and is like that of Figs. 1 and 2 in all respects except that in addition to the two working electrodes 44 and 45 corresponding to the electrodes iii-ll of Figs. 1 and 2, a third workll'lg electrode 45 is provided, having an individual current lead 49 and a heater element 50 'insulated therefrom and connected in common with the heaters of the working electrodes 44, 45 and the heater of the auxiliary electrode 51.

The modification 43 is shown in Fig. 4 asreplacing the two tubes '33 and 34 in a signaling system substantially identical with that of Fig. 3. Thus in Fig. 4 only four electrodes including the auxiliary electrode are used as against six electrodes in the arrangement of Fig. 3, and all in the one tube. The central electrode 46 operates to establish conduction, through electrodes 44 and 45, between the output transformer 4| and both transducers 3l--38 simultaneously. This condition of conduction takes place only upon attainment of a given signal voltage output from the transformer 4|, and ceases after the signal voltage is momentarily cut off and remains below a iven minimum, thus effectively protecting the highly sensitive receiving stations from low voltage, noise-producing electrical disturbances reaching the output terminals of the transformer from the preceding network of circuits and apparatus, the non-conducting condition of the tube also operating to prevent the relatively low voltage electrical output of one transducer from reaching the receiving station of the other back through the common connection of the transducers with the signal generator.

While certain specific uses for the device have 1 been described by way of example, it will be clear that the device will have many other uses, and ,whilebut two specific embodiments of themvention have been herein shown and described forthe sake of disclosure, it is to be understood factured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

A discharge device comprisin an-envelope containing an ionizable gas, a plurality of thermioni' c emissive working electrodes, a protective thermionic emissive electrode, and an indirect heater element foreach electrode, ,all said working electrodes being insulated from each other and from said heater elements, said protective electrode b eing of lowerwo'rk function than said heater elements and directly electrically connected to all said heater elements, wherebyany difference in potential between the protective electrode and any working electrode will be maintained the same as that between that working electrode and the heater elements so that any ions oherwise tending to pass to the heater elements will in preference pass to the lower work function protective electrode;

THOMAS F. JONESQ file of this patent:

Number Name Date 1,738,420 Charlton Dec. 3, 1929 1,869,560 Horn Aug. 2, 1932 1,872,567 Beck Aug. 16, 1932 1,908,308 Bolan May 9, 1933 1,980,596 Poor Nov.:13, 1934 2,097,261 Spanner Oct. 26, 1937 2,348,814 Herriger May 16, 1944 2,452,626 -Atlee Nov. 2, 1948 FOREIGN PATENTS 7 Number Country 7 Date UNITED STATES PATENTS France Apr. 14, 1930 

